1. Field of the Invention
This invention pertains to anti-pain medicaments comprising at least one NGF antagonist compound that selectively inhibits the association of NGF with TrkA, without appreciably inhibiting the association of NGF with p75 Preferably, these NGF antagonist compounds will comprise an antibody or fragment thereof (including Fab fragments and other monovalent agents identified infra) having binding specificity to human Nerve Growth Factor (hereinafter “NGF”), and methods of using one or more of said NGF antagonist compounds, e.g., antibodies and fragments thereof to treat pain in an individual. While antibodies and fragments are exemplified, it is anticipated that other NGF antagonists may be selected using appropriate binding and/or functional assays which possess similar antagonist properties, e.g., polypeptide fragments of NGF or TrkA, small molecules, antisense RNA's and silencing RNA's. and the like that selectively inhibit the association of NGF with TrkA, without appreciably inhibiting the association of NGF with p75 These compounds, e.g., antibodies and antibody fragments may be used as a monotherapy to treat or prevent different types of pain in a subject in need thereof when administered alone or in association with another active agent, e.g., a NSAID or opioid analgesic. More specifically the invention pertains to anti-human NGF antibodies or fragments thereof including monovalent agents that inhibit the association of NGF with TrkA, without appreciably inhibiting the association of NGF with p75. These antibodies and fragments, e.g., monovalent agents, may be modified to affect circulation half-life, such as via the attachment of PEG or other polymers or by attachment of other moieties such as detectable agents or functional agents. These monovalent agents include by way of example Fab, Fab′, Fv, scFv fragments, SMIPs (small molecule immunopharmaceuticals), camelbodies, nanobodies, IgNAR, a monovalent antibody molecule analogous to MetMab, or one or more combinations thereof.
In addition, and related thereto the invention pertains to novel methods of treating pain or eliciting an analgesic effect in an individual, comprising administering an effective amount of any NGF antagonist compound that selectively inhibits the association of NGF with TrkA, without appreciably inhibiting the association of NGF with p75 Preferably, these antagonist compounds will comprise an anti-human NGF antibody or fragment thereof which inhibits the association of NGF with TrkA, without appreciably inhibiting the association of NGF with p75. The present invention further optionally includes methods of treating pain further including the administration of a second anti-NGF antibody or fragment that inhibits the association of NGF with p75, that may in addition inhibits the association of NGF with TrkA.
2. Description of Related Art
Nerve Growth Factor (NGF) (also known as beta nerve growth factor (Beta-NGF)) is produced as a mature protein of 222 amino acids in length, following cleavage of a 18 amino acid signal peptide. The gene encoding NGF is located on chromosome 1p13.1. A biologically active form of NGF is a secreted protein which homodimerizes and is incorporated into a larger complex. NGF is a member of the neurotrophins (NTs), which are a group of structurally-related proteins further including brain-derived neurotrophic factor (BDNF), NT-3, and NT-4/5. (Wyman et al., Gene Therapy (1999), 6:1648-1660). NTs support the survival of specific types of neurons and neurotransmitter systems, being produced by cells that are targeted by innervating neurons. Id. Basal forebrain, substantia nigra, brain stem, cortex, and spinal cord are nervous system regions having demonstrated responsiveness to NGF. Id.
All NTs bind to a low-affinity receptor identified as p75. (Sarchielli et al., Expert Rev. Neurotherapeutics (2004), 4(1):115-127). NGF selectively binds to, and displays a high affinity for, the high affinity neurotrophin receptor TrkA. Id. It has recently been demonstrated that NGF acts through its low-affinity receptor p75 in a developmentally-regulated signaling pathway necessary for myogenic differentiation and muscle repair in vivo. (Deponti et al., Mol. Biol. Cell (2009), 20:3620-3627).
NGF has also been demonstrated to interact with pain-signalling systems in adult animals, and is responsible for hyperalgesia when administered either locally or systemically in many species. (Sarchielli et al., Expert Rev. Neurotherapeutics (2004), 4(1):115-127). NGF has been shown to induce a pain-like response when infused into the CSF in rats, and has been demonstrated to maintain chronic pain. Furthermore, NGF has been demonstrated to contribute to the development of mechanical allodynia occurring 8-12 hours later, and to the secondary pain response. Id.
Pain may often be addressed through the administration of certain narcotics or non-steroidal anti-inflammatory drugs (NSAIDs). However, the administration of these treatments may occur at the cost of certain negative consequences. NSAIDs have the potential to cause kidney failure, intestinal bleeding, and liver dysfunction. Narcotics have the potential to cause nausea, vomiting, impaired mental functioning, and addiction. Therefore, it is desirable to identify alternative treatments for pain in order to avoid certain of these negative consequences.
NGF is believed to play a role in a multitude of diseases and disorders, including but not limited to pain associated with a broad range of diseases and disorders, such as pain associated with cancers, neuropathic pain, and neurogenic pain. Due to the perceived involvement of NGF in a wide range of pain-related diseases and disorders, there remains a need in the art for compositions and methods useful for preventing or treating diseases and disorders associated with NGF, and particularly those associated with pain. Particularly preferred anti-NGF compositions are those having minimal or minimizing adverse reactions, such as inflammation when administered to the patient. Compositions or methods that reduce or inhibit diseases or disorders associated with NGF, such as pain, are beneficial to the patient in need thereof.